The purpose of this research is to compare arthrodesis with arthroplasty in the treatment of end stage ankle arthritis (ESAA) via Randomized Controlled Trial (RCT). The absence of this comparative outcome information is crippling the development of clinical guidelines. The American Academy of Orthopaedic Surgeons (AAOS) abandoned plans this year to publish clinical guidelines for treatment of ankle arthritis because of a lack of evidence. Arthrodesis is considered the primary/gold standard treatment in the absence of evidence or quality functional outcome data due to the historical lack of an acceptable surgical alternative. Currently, the treatment selection is based on the training and preference of the surgeon, and the preference of the patient. Only a few prospective cohort studies have compared the safety and efficacy of these treatment options, and no RCTs have been published. Now that a respectable treatment alternative to arthrodesis is available, an RCT is the logical next step. In response to the need for an RCT, the experimental focus of this research is two-fold: 1) to compare arthrodesis versus arthroplasty treatment outcomes in similar patient populations and 2) to identify intrinsic and extrinsic prognostic factors of arthroplasty patients with successful and unsuccessful outcomes for the purpose of establishing clinical indications and contraindications for arthroplasty. This will be accomplished by measuring pain, ankle function, general health, patient satisfaction, and physical activity based on step counts at 3, 6, 12, and 24 months after surgery in a multi-site RCT. It is established that some potential subjects (we estimate 50% based on pilot data) will not want to undergo random allocation where blinding is not possible and one treatment represents relatively new technology;crossover after randomization and demoralization can substantially skew results under these circumstances. The study is powered to answer the primary Specific Aims based on the randomized subjects only, but we will allow those unwilling to randomize to enroll with their preferred treatment choice, and they will be analyzed as part of a Comprehensive Cohort Design. Additional subjects from the Comprehensive Cohort Design will allow us to determine if motivation affects outcome and will provide additional study power to determine which baseline factors are associated with positive and negative outcomes to better determine indications and contraindications for each treatment. To meet the enhanced numbers required to power for the randomized subjects alone, we have increased the number of participating sites from three to five. To assure parity in surgical skill in both treatments, we employ only surgeons with a minimum 5 years experience and performance of at least 30 ankle replacements. To meet budget limitations imposed by adding more sites, the surgeons at these sites have agreed to volunteer the time needed to complete the study. Though there are many issues that can only be answered by a longer study, we expect to answer our stated aims within this follow up. PUBLIC HEALTH RELEVANCE: A dramatic change is taking place in the treatment of end stage ankle arthritis. The advent of successful (in the short term) second generation prosthetic ankle joints is changing the treatment paradigm. Both physicians and patients are in need of good quality evidence comparing arthroplasty to the "gold standard" of arthrodesis to guide treatment. This study should provide this important information and provide data on which patients are better candidates for one treatment over another.